According to this article, 16 teams use the zone blocking scheme, and 16 use man/power blocking. As far as 4-3 and 3-4 base defense, it says 20 teams use a 4-3 and 12 teams a 3-4 defense.
I went through the current NFL standings to compare the records of teams who use zone blocking to those who use power blocking. Of all the 1st place teams, 4 use zone and 4 use power. Of the 2nd place teams, 4 use zone and 4 power. The 3rd place teams, 4 zone - 4 power. The 4th place teams, 4 zone - 4 power.
For what it's worth, of the teams the Raiders have left to play this year, the Chiefs are a zone blocking team. The Panthers are zone, and the Chargers are power blocking.
http://nflsfuture.com/2012/03/28/team-by-team-offensivedefensive-schemes/
